My Favorite ENVI Extensions

The Extensions Library, formerly Code Contribution, is a treasure trove of tools for ENVI and IDL. Some are written by Exelis VIS staff (tech support, sales engineers, product managers and software engineers) others by customers. Most tools are written to meet a specific customer need or an internal need or support a specific data type. These tools for ENVI can be dropped directly into the extensions folder for ENVI 5 tools C:\Program Files\Exelis\ENVI53\extensions or the save_add directory for ENVI Classic applications C:\ProgramFiles\Exelis\ENVI53\extensions or for IDL specific tools, the code just needs to be in your IDL path. Some code is source, some is distributed as binary Sav files. Users who want to publish their code on the extensions library can contact support@exelisvis.com and send their code in sav or pro form (there is a short form to fill out). You will need to use your Exelis VIS login to get to the Extensions Library. Here is a list of some of my favorite tools:

This tool drops into the ENVI 5 interface and allows users to directly browse the Airbus Defense and Space Geostore for Spot and Pleiades data. The nice thing here is you can browse for data in the context of other imagery or vector layers you might have inside of ENVI to make sure you’re getting data in the right area with the correct parameters, such as look angle to meet your needs exactly. There’s also the option to send an email to Airbus Defense and Space to get a quote for the imagery you’re interested in. So one stop shopping directly from ENVI.

Written by Eduardo Iturrate—Eduardo’s goal for this and the next bit of code I mention is bringing programming to the masses to make it easy to script as well as learn by example. The ENVI source code generator allows you to open data, do something to it (classify, segment, band math etc.) and create an output. So it generates the code to do this and et voila you have a batch script with a few button clicks. And while this batch script is a great utility, the source code it generates is a great way to self-teach ENVI programming.

IDL’s key value has always been data access, analysis, and visualization. This powerful tool guides you to open a certain data type, do some sort of analysis or processing, and create a 2 or 3-d visualization/output. This tool is incredibly powerful for the non programmer who has need to access scientific data, doesn’t know the tricks of manipulating and analyzing those data, and would like a sandbox for creating output visualizations. The resulting program can be run again andagain or be used as an example to learn from. The bottom line, if you’re a beginner with IDL, this code will save you a ton of time and take a lot of anxiety out of learning a new language.

This tool allows you to create professional looking reports directly from ENVI including adding logos, annotation, legends and backgrounds. It’s great tool when you’recreating image products in ENVI that are actionable and need to be shared with others on your team for use in decision making.

This is a tool written by Mari Minari from our tech support team to fill in the Scan Line Corrector off data from Landsat 7. While ultimately infill is not ideal, given the failure of this component on Landsat 7, this tool allows one to still make use of these data. This tool follows the USGS methodology, so it’s the best option if one must work with SLC off data. At the moment this utility is for the Classic ENVI interface, but works just great there.

Dr. Devin White, one of my favorite ex-VIS employees, has found great success with supercomputing at Oak Ridge National Lab. Devin hosts his ENVI library on GitHub and has some great tools for Modis, VIIRS, Ortho processing and more. He writes fast, effective code—truly a “geter’done” resource.

An oldie but goodie. Developed by our ENVI product manager Adam O’Connor, the Anaglyph Generation tool for DEMs and imagery creates red/blue results for viewing with 3-d glasses. It runs in the 5 interface or classic.

There are many more utilities and tools on the Exelis VIS website Extensions library, but these are the ones I use most frequently. And remember, IDL sav files and can be run freely with the IDL virtual machine.